Method of producing tank balls



1922 2 Sheets-Sheet 1 A. H. CANFIELD METHOD OF PRODUCING TANK BALLS Filed Nov.

fir'y l- April 28; I925.

attuned April 28, 1925.

A. H. CANFIELD METHOD OF PRODUCING TANK BALLS Filed Nov. 2, 1922 2 Sheets-Sheet 2 Patented Apr. 28, 1925.

i UNITED STATES PATENT OFFICE.

METHOD or rnonucmo ram: BALLs.

=. Application filed November 2, 1922. Serial No. 598,593.

To all whom it may concern:

Be it known'that I ALBERT H. CANEIELD, a citizen of the United States, residing at Bridgeport, in the county of Fairfield and State of Connecticut, have invented certain new and useful Improvements in Methods of Producing Tank Balls, of which thefollowing is a specification.

This invention pertains to an improved method of producing tank balls and has for its main object the production of a -superior ball without scams or joints and this in what may be termed a single step process.

The apparatus whereby the method may be carried. out, as well as various forms of balls falling within my invention, are illustrated in the annexed drawings, wherein, Fig. 1 is a sectional elevation of the upper portion of the mold, the core or spreader being shown in full;

Fig. 2 a sectional view of the lower por tion of the mold, the spud and the sheet of material which forms the outer relatively hard or stiff face of the upper portion of the finished ball being shown in section, while the mass, from which the body of the ball is formed, is shown in full;

Fig. 3 is a sectional elevation of the mold section assembled, with .the molded ball likewise shown in section;

' Fig. 4 a sectional elevat on of the completed ball;

Fig. 5 a sectional view of the upper sec tion of the mold, with the core piece removed;

Fig. '6 a face view thereof, looking down into the mold cavity; Fig. 7 a perspective view of the core piece; t Fi 8 a sectional view of the lower moldmem her;

Fig. 9 a face view thereof looking into the mold cavity;

Fig. 10 a detail sectional view illustrat ing a modified manner of positioning the spud; and f Fig. 11 a sectional elevation of a slightly modified form of ball. I Y

Referring first to Figs. 1 to 9, inclusive, 1 denotes the upper mold member provided, as is usual, with a pluralityof guide pins 2 adapted to pass into openings 3 formed in' the lower mold section or member 4 to effect proper registry of the mold members when they are moved toward each other to closed position in the act of shaping and producing the ball. It is to be understood that-the terms upper and lower, as applied to the mold sections, are merely relative and is employed merely as a matter of convenience, as their position might be reversed, though the operation of placement of. the materials and parts :could not be so conveniently efl'ected as when the parts are used in the relation shown and described.

The upper member 1 is provided, in its 1 under side, with a cavity 5 substantially semi-spherical in form, the upper portion of the curvature being interrupted, however, by an inwardly projecting portion 6, presenting a fiat inner face 7 and producing a shoulder 8. A round opening 9, formed coaxial with the cavity 5 and projection 6, extends through the moldsection, and is designed to receive the stem 10 of the core piece, shown in Figs. 1, 3 and .7.

Said core piece has the form which it is desired to impart to the interior of the ball, and may be said to comprise a frustoconical section 11, and a rounded section 12, substantially hemi-spherical in contour, and formed'upon a radius somewhat smaller than that of the mold cavity 5. The upper portion of the. core is formed with a fiat face 13 and a land or shoulder 14, the di': ameter of the former being the'same as that of the flat face 7.

When the core is positioned in the mold section- 1 the stem 10 passes into the opening 9 and the flat face 13 abuts the face 7 on the mold section. With the parts thus positioned there is formed between the hemi-spherical portion 12 of the core and the adjacent wall of the cavity 5, a space or chamber, denoted by 15, which, atv its upper end, is somewhat enlarged, as at 16,

(see Fig. 1). I p y.

The lower mold section 1 is provided with an .inverted frusto-conical cavity 17,

from the bottom of which there extends upwardly a pin 18 adapted to receive and position the usual spud 19 employed in tank bulbs. The pitch-of the cone shaped cavity 17 is somewhat more obtuse than is that of the cone shaped section 11 of the core, so that when. said core element extends down into the cavity 17 the walls of the two elements do not stand in parallelism, thereby "producing a space between the walls of inting faces of the mold sections.

creasing measurement toward the bottom of the cavity or toward the spud. I

It is conceivable, of course, that the same grade and character of stock' throughout may be employed to produce a ball with the mold as above described, but I- prefer to produce a ball having its head or upper portion relatively hard ,as compared to the lower or seating portion. To this end, after having placed the spud 19 upon. the pin 18,

I impose thereover and thumb down with-- in the cavity 17, a sheet or disk of rubber 20, (Fig. 2) so compounded that when vulcanized it becomes relatively hard or stiff. If desired, the disk which is preferably formed with a central aperture 21 may be forced down and around the spud so as to engage the same, but so far as actual results are concerned, this is immaterial. I next place upon the sheet or disk 20 a cylindrically shaped block of relatively softcuring rubber, denoted by 22, and'when this is done the two mold sections which are hot, to a greater or less degree, are brought together. 4 tacts the block 22, and causes the same to flow laterally, and likewise to force disk 20 downwardly around the spud and into close and intimate contact with the wall of cavity 17. At the same time the material-in block or mass 22 passes up along the face of the cone shaped element 11 of the core, and finally flows into and fills the space or chamber 15 and the enlarged annular space 16'.-

The disk and block will be so proportioned as to mass as to fully fill all the mold cavi ties, and should there be any excess, it will be extruded outwardly between the abut- The mold is then clamped and subjected to such a degree of heatas will properly vulcanize the rubber stock. When vulcanization has been effected the mold sections are separated,'and by reason of the core being embraced within the ball, the latter will be withdrawn from the cavity 17, and carrying'with it the embedded spud. The core is then knocked from the mold section 1 by tapping upon the outer end of pin 10, and this leaves the finished ball, comprising the upper frustoconical section 23, and the lower substan-.

The lower end 11 of the core 0011-.

It may be read chamber'16, and this rib or enlargement prevents the ball from being torn when removed from the core, and likewise stiifens the'same against collapsea It will also be noted, upon reference to Figs. 3 and 4, that the soft rubberbody of t e upper section of the ball, is thicker toward .the spud end than it is at-the other portions.- In other words, by reason of the difference in angularity between the cavity 17 andthe frusto-conical section 11 of the core, the upper portion of, suchv soft rubber body or that which lies within the hard outer facing, is relatively thick, 0r increases in thickness toward ,the spud.

Inasmuch as the ball is produced in a single heat and there is no preforming or premolding of separate sections or halves, requiring subsequent joining with. a consequent scam, the method is at once simple and effective. The material in the block or charge 22 is coextensive of the upper and lowerportions' of the ball, and this without the presence of any seams or joints. The outer upperendfacing formed from the disk 20 becomes amalgamated with the underlying material, and, in practice, unless different colored stock is employed in the disk and charge 22, the line of juncture is imperceptible. v

- In Fig. 10 a slightly modified manner of mounting the spud is shown. In this instance, thespud 19 has threaded into it a short pin or stem 28, which passes freely .down through an opening formed in the bottom section of the mold, the free fit allowing for the venting. of the air.

In Fig. -11 a slightly modified formation of the tank bulb is illustrated, wherein a layer of fabric, denoted by 29, is shown as lying between and embedded in the adjacent faces or portions ofthe inner relatively soft rubber and the harder outer facing body. This may bereadily embodied in the structure by imposing a 'piece of frictioned fabric upon the disk 20 before the body charge 22 is placed thereon. The presence of this fabric may be found-advantageous in tank balls of the larger sizes.

While it is preferred to employ a core piece produced as an integral structure, it is to be understoood that in practicing the as such, the same being divided out of this application pursuant to the requirement of division made by the Patent Office. The cla ms directed to the article or ball form the basis of my divisional application filed on v or about March 24, 1925, Serial No. 18,013.

. tion; placing on the disk a body of soft hat is claimed is,- 1. That method of forming tank balls which consists in'placing within a cavity formed in a mold section, material sufiicient to produce the ball in its entirety forcing down onto said material a second mold section, said second section having a core mounted in a cavity formed therein and inspaced relation to the walls of the cavity, said core likewise having an outwardly extending portion which portion when the mold sections are brought together which consists in placing within a cavity formed in a mold section, material sufli cient to produce the ball in its entirety and forcing down onto said material a second mold section, said second section having a core mounted in 'a cavity formed therein and in spaced relation to the walls of the cavity, said core likewise, having an outwardly extending portion which portion when the mold sections are brought together contacts the material and causes a flow thereof throughout the cavities in the mold, and finally vulcanizing the ball thusproduced I Y 3. That method of producing tank balls having a relatively stiff upper portion and a softer seating portion, which consists in placing a disk, or sheet of hard curing rubber within a cavity formed in a mold seccuring rubber in a quantity sufficient to be coextensive of the upper and lower portions of the ball, thereafter pressing a secondmold section against the other, said second mold sectlon carfying'a core which causes the material to flow into and fill the cavities formed between it and the walls of the cavities in the mold sections and finally vulcanizing the ball thus produced.

4. That method of producing tank balls, which consists in placing a body of relatively hard curing stock in a female mold, imposingthereon a body of relatively soft curing stock, bringing a male mold, surrounded by a stock receiving cavity, into pressing relation to the stock and finally vulcanizing the ball thus roduced.

5. That method of pro ueing tank balls, which comprises the imposing of a body of soft curing rubberupon a sheet of hard curing rubber andsubjecting the same to molding pressure and heat within a mold structure suficient to cause the soft rubber to flow into and throughout the mold cavityand simultaneously produce a conform ing of the sheet to the adjacent wall of the mold and a coalescence thereof With the soft body.

6. That method of "producing tank balls having a relatively stiff top with a spud embedded therein, which comprises positioning a stud within a mold; placing a sheet of. relatively hard curing rubber "thereover, said sheet being of such size as to. be coextensive of the upper outer face of the finished ball; imposing a 'body'of soft curing rubber on the sheet,

said body being of. suflicient volume as to produce the lower] soft portion of the ball and an-inner covering or lining for the upper portion of' the ball; subjecting the sheet and body to molding pressure and heat witliin*a'*--moldstructure sufficient to cause the soft; rubber to flow into and throughout thei mold cavity, and simultaneously produce aconforming of the sheet to the adjacent wall-of the mold and a coalescence thereoffwith the soft body and finally vulcanizing the ball thus Produced.-

'7. Thatmethodof producing tank balls, having a relatively stifi top, which consists in lining or facing'a cavity formed within a half mold se'ctioniwith' a sheet of relatively hard curing rubber; imposing a body of soft curing rubber on the sheet thus positioned; andfinally bringing a core, carried by a second half-mold section and held in spaced relation thereto, against saidbody and thereby causing, as the. mold sections are closed, a flow of'the rubber body over the sheet and into and throughout the mold cavities. y

In testimony whereof I have signed myname to this specification.

ALBERT HOMER CANFIELD. 

